Impact of chlortetracycline and sulfapyridine antibiotics on soil enzyme activities.

Pharmaceutical antibiotics are frequently used in the livestock and poultry industries to control infectious diseases. Due to the lack of proper guidance for use, the majority of administrated antibiotics and their metabolites are excreted to the soil environment through urine and feces. In the present study, we used chlortetracycline and sulfapyridine antibiotics to screen out their effects on dehydrogenase, alkaline phosphatase and urease activity. Factorial experiments were conducted with different concentrations of antibiotic (0, 10, 25 and 100 mg kg-1 of soil) mixed with soil samples, and the enzyme activity was measured at intervals of 1, 4 and 21 days. The results show that the chlortetracycline and sulfapyridine antibiotics negatively affect the dehydrogenase activity, but the effect of sulfapyridine decreases with time of incubation. Indeed, sulfapyridine antibiotic significantly affect the alkaline phosphatase activity for the entire three-time interval, while chlortetracycline seems to inhibit its activity within 1 and 4 days of incubation. The effects of chlortetracycline and sulfapyridine antibiotics on urease activity appear similar, as they both significantly affect the urease activity on day 1 of incubation. The present study concludes that chlortetracycline and sulfapyridine antibiotics have harmful effects on soil microbes, with the extent of effects varying with the duration of incubation and the type of antibiotics used

Comparison of Pattern Recognition, Artificial Neural Network and Pedotransfer Functions for Estimation of Soil Water Parameters

This paper presents the comparison of three different approaches to estimate soil water content at defined values of soil water potential based on selected parameters of soil solid phase. Forty different sampling locations in northeast of Iran were selected and undisturbed samples were taken to measure the water content at field capacity (FC), -33 kPa, and permanent wilting point (PWP), -1500 kPa. At each location solid particle of each sample including the percentage of sand, silt and clay were measured. Organic carbon percentage and soil texture were also determined for each soil sample at each location. Three different techniques including pattern recognition approach (k nearest neighbour, k-NN), Artificial Neural Network (ANN) and pedotransfer functions (PTF) were used to predict the soil water at each sampling location. Mean square deviation (MSD) and its components, index of agreement (d), root mean square difference (RMSD) and normalized RMSD (RMSDr) were used to evaluate the performance of all the three approaches. Our results showed that k-NN and PTF performed better than ANN in prediction of water content at both FC and PWP matric potential. Various statistics criteria for simulation performance also indicated that between kNN and PTF, the former, predicted water content at PWP more accurate than PTF, however both approach showed a similar accuracy to predict water content at FC

Effects of mixed plantation of alder and poplar on population of Frankia nodulation in soil

Nowadays, nitrogen-fixing tree species are often planted in combination with poplar to provide nutrients, though this can reduce the number of host plants and have a negative impact on soil Frankia population. In order to study the effects of mixed plantation of Caucasian alder (Alnus subcordata) and poplar (Populus deltoides) on Frankia nodulation potential, an experiment was carried out within a randomized block design. Five different mixtures of 17–years old P. deltoides (P) and A. subcordata (A) (100A, 70A30p, 50A50P, 30A70 and 100P) were established in Safrabasteh Poplar Research Station in Guilan province of Iran. The results showed that the presence of alder in mixture with poplar positively affected the diameter at breast height (DBH) and height of poplar trees. Mixed plantations with alder can improve Soil pH and the amount of soil nutrients and organic carbon. Furthermore, foliar nutrient concentrations of poplar trees were higher in mixed plantations than in pure plantations. The results of Frankia population analysis showed significant difference between the soils across different species mixture classes. The highest and lowest levels of Frankia population were observed in the rhizosphere soil of pure alder (49.17 g-1 soil) and pure poplar (0.89 g-1 soil), respectively. The Frankia population was negatively correlated with amounts of available P and K, yet it was positively correlated with pH. In addition, Frankia population showed positive and negative correlations with alder DBH and height, respectively. These results confirmed the effects of plant-host density on the viability and population of Frankia

Роль нанотехнологий в совершенствовании растениеводства

Today, green nanotechnology has great importance due to the presence of different modes of restrictive action against various pathogens such as fungi and bacterial species. The use of nanomaterials has recently increased in agriculture and plant-tissue culture thanks to their unique different properties such as; magnetic, electrical, mechanical, optical, and chemical properties. Optimum use of iron increases protein content in the wheat grain. They also enhance plant growth by improving disease resistance and increase stability of the plants by anti-bending and deeper rooting of crops. It has been reported by many researchers that Nano-fertilizers significantly influenced the seed germination which demonstrated the effect of Nano fertilizers on seed and seed vigor. Chemical methods have been used for the synthesis of nanoparticles. Developing Nano-biotechnology is generating interests in research towards eco-friendly, cost effective and biological synthesis of nanoparticles. Nanoparticles systems have been combined into plant fungal disease controlpractices. Using nanoparticles as biosensors in plant disease diagnostics is also illustrated.Использование наноматериалов в последнее время возросло в сельском хозяйстве и культуре тканей растений благодаря их уникальным свойствам: магнитным, электрическим, механическим, оптическим и химическим. Приведен обзор исследований, посвященных применению нанотехнологий в растениеводстве, подтверждающих в частности, что наноматериалы усиливают рост растений, повышают сопротивляемость болезням и устойчивость растений, предотвращая изгиб и обеспечивая более глубокое укоренение сельскохозяйственных культур, а оптимальное использование железа, например, увеличивает содержание белка в зерне пшеницы. Многие исследователи сообщают, что наноудобрения значительно повлияли на всхожесть семян, что продемонстрировало влияние наноудобрений на семена и их энергию. Отмечено, что для синтеза наночастиц используются химические методы, а развитие нанобиотехнологии вызывает интерес к исследованиям, направленным на экологически чистый, экономически эффективный биологический синтез наночастиц. Сегодня зеленые нанотехнологии обеспечивают различные способы воздействия на патогенные микроорганизмы: грибы и многие виды бактерий. Показано применение систем наночастиц в практике борьбы с грибковыми заболеваниями растений, использование их в качестве биосенсоров в диагностике заболеваний растений

Phenotypic and molecular characterization of Sinorhizobium meliloti strains isolated from the roots of Medicago sativa in Iran

Introduction: The Rhizobium-legume interaction leads to biological nitrogen-fixation and increases nitrogen of soil. The aim of this study was to characterize the properties of Sinorhizobium isolates from the roots of alfalfa plantsin Iran. Materials and methods: Bacteria were isolated in yeast extract mannitol Agar and confirmed by plant infection test. After evaluation from the point of morphological and biochemical properties, a fragment of 16S rDNA gene with a size of approximately 1500 base pair was amplified using fD1 and rD1 primers. PCR (polymerase chain reaction) products were analyzed for digestion pattern by Taq1 endonuclease. Results: 63 bacteria were isolated from homogenized nodules. 42 isolates generated nodules in three replicates in infection test. Of the 42 isolates 8, were resistant to salinity. Seven isolates had better growth than others at pH 4. All isolates were resistant to CuCl2 (0.5 mmol), CdCl2 (0.65 mmol), MnSO4 (0.75 and 1.5 mmol) and ZnSO4 (0.125 mmol). Isolates S3Q and S22K were more resistant to salinity, acidity, temperature and heavy metals stresses. PCR products of all bacteria had the same restricted profile after digestion by Taq1 nuclease. Discussion and conclusion: The results showed that among isolated bacteria, there were some differences in the resistance to salinity, acidity, temperature and heavy metals stresses.  Identification of native strains of rhizobia, especially strains resistant to salinity, temperature, heavy metals and acidity could be valuable due to their potentiality for using biological fertilizers in harsh conditions

Geogenic and anthropogenic sources of potentially toxic elements in airborne dust in northeastern Iran

Little attention has been given to the nature and sources of airborne dust affecting northeastern Iran. The objectives of this study were to examine the concentrations of selected potentially toxic elements (i.e., Cr, Cu, Fe, Mn, Ni, Pb, and Zn), distinguish geogenic from anthropogenic sources, and assess the pollution intensity. A total of 600 samples were collected at 50 locations 12 times between May 2014 and April 2015 for fallout rate; 250 of these samples were selected for geochemical analysis. Mean dust concentrations of Cu, Pb, and Zn were found to be higher in autumn compared to spring as well as higher in the most populous cities. Results suggested that Ni, Cr, Mn, and Fe have come from mainly natural geologic sources, while concentrations of Cu, Pb, and Zn in the dust were associated with anthropogenic sources. Enrichment factors showed minimal to significant enrichment for Cu and Pb and moderate to very high enrichment for Cr, Ni, and Zn. The mean geo-accumulation index revealed that the contamination levels for Cu, Pb, and Zn peaked during autumn. In addition to industrial and traffic sources, seasonal differences in meteorological conditions can create frequent and persistent thermal inversions that at ground level can result in increases in Cu, Ni, Pb, and Zn concentrations during autumn. Because of the diversity of geology and terrain in combination with significant seasonal shifts in winds over this region, this study highlights the need to consider both geogenic and anthropogenic sources in evaluating pollution risks in northeastern Iran

Spatial and temporal variations of airborne dust fallout in Khorasan Razavi Province, Northeastern Iran

Dust deposition rates depend mainly on the rate of dust supply, climatic conditions, and topography in the source and sink areas. The objective of this study was to investigate the role of these variables in the spatial and temporal variation of airborne dust fallout in Khorasan Razavi Province, Northeast Iran. Airborne dust samples were collected monthly from May 2014 to April 2015. Dust fallout rate was modelled as a function of air temperature, precipitation, relative humidity, wind velocity and distance from source regions. The lowest and highest rates of atmospheric dust fallout occurred in December and June, with average amounts of 9.97 gm(-2) and 20.96 gm(-2), respectively. The strongest winds were observed in June immediately following a relatively humid period (i.e., March-May) with considerably higher precipitation and lower evaporation. Spatial distributions showed that the highest dust fallout rates occurred in the southern and western parts of the province-areas adjoining the vast playas. During the spring and summer season, the distance from the nearest playa was a key factor that explained more of the variation in dust flux than climatic parameters. Both runoff by fresh sediment moved onto the surface of the playa and the formation of loose sediment on the surfaces of wet playas are mechanisms that can increase dust emissions. The lowest deposition rates were observed in the mountainous region in the north of the province likely due to higher precipitation, atmospheric humidity, and soil moisture. This work represents the first baseline dust data for Khorasan Razavi Province and may be useful in evaluating the effects of future land use and climate change on aeolian land surface processes